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Indexed by:期刊论文

Date of Publication:2017-09-27

Journal:JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

Included Journals:Scopus、SCIE、EI、PubMed

Volume:65

Issue:38

Page Number:8319-8330

ISSN No.:0021-8561

Key Words:baicalein; acarbose; synergistic inhibition; postprandial blood glucose; alpha-glucosidase

Abstract:The inhibition of porcine pancreatic alpha-amylase and mammalian alpha-glucosidase by 16 individual flavonoids was determined. The IC50 values for baicalein, (+)-catechin, quercetin, and luteolin were 74.1 +/- 5.6, 175.1 +/- 9.1, 281.2 +/- 19.2, and 339.4 +/- 16.3 mu M, respectively, against alpha-glucosidase. The IC50 values for apigenin and baicalein were 146.8 +/- 7.1 and 446.4 +/- 23.9 mu M, respectively, against alpha-amylase. The combination of baicalein, quercetin, or luteolin with acarbose showed synergistic inhibition, and the combination of (+)-catechin with acarbose showed antagonistic inhibition of alpha-glucosidase. The combination of baicalein or apigenin with acarbose showed additive inhibition of alpha-amylase at lower concentrations and antagonistic inhibition at a higher concentration. Kinetic studies of a-glucosidase activity revealed that baicalein alone, acarbose alone, and the combination showed noncompetitive, competitive, and mixed-type inhibition, respectively. Molecular modeling revealed that baicalein had higher affinity to the noncompetitive binding site of maltase, glucoamylase, and isomaltase subunits of alpha-glucosidase, with glide scores of -7.64, -6.98, and -6.88, respectively. (+)-Catechin had higher affinity to the active sites of maltase and glucoamylase and to the noncompetitive site of isomaltase. After sucrose loading, baicalein dose-dependently reduced the postprandial blood glucose (PBG) level in mice. The combination,of 80 mg/kg baicalein and 1 mg/kg acarbose synergistically lowered the level of PBG, and the hypoglycemic effect was comparable to 8 mg/kg acarbose. The results indicated that baicalein could be used as a supplemental drug or dietary supplement in dietary therapy for diabetes mellitus.